Electromagnetically operated vacuum switch



Jan. 7, 1936. IE. Roz'UMEK ELECTROMAGNETICALLY OPERATED VACUUM SWITCH Filed May 23, 1933 o0 lrl 4 30 8 Z Z 2 w a Z7 @4Min 5 SMO ,if f ,c 1. Z/ f 470 t Cbt /w/ n 4l. 4 HHHHH.. u 3 0 7 Il 9 70o 0900 0 F Mm 52 5 22 m82 Z m Patented Jan. 7, 1936 UNITED STATES PATENT OFFICE Ernst Rozumek, Berlin-Lichterfelde, Germany Application May 23, 1933, Serial No. 672,436

In Germany August 6, 1931 6 Claims.

It is known that for operating vacuum switches only very small energies are required per se. The contacts of vacuum switches, however, have a strong tendency to become welded together owing to the absence of any form of oxide. Should such a welding together of the contacts occur, relatively large powers are required for separating the contacts. When vacuum switches are operated electromagnetically there is a possibility that they may on occasion not break the circuit if the magnet coils areonly made sufficiently powerful to satisfy the normal working conditions. For this reason it is necessary to make the coils unnecessarily strong and consequently to increase the size l5 of the switches considerably. Even then there is no certainty that should the contacts become particularly strongly welded'together they will actually be separated.

Experience has shown that although the weldin g place between the contacts in a vacuum op poses a considerable tensile strength to a steady or slow and gradually increasing load, it is nevertheless relatively brittle and can therefore be easily destroyed by a blow or impact. Accord- 95 ing to the invention electromagnetic tensile forces are therefore not caused toact directly on the contacts or their supports, but an armature of relatively great mass is provided, which through the electromagnetic forces or an electromagnetically stressed spring opens the contacts 'with a jerk by means of the kinetic energyvstored in it.

The invention is illustrated by way of example in the accompanying drawing, in which Fig. l is a longitudinal section through the arrangement according to the invention,

Fig. 2 a partial longitudinal section through another constructional form and Fig. 3 a longitudinal section through a further constructional form.

I is a stationary contact provided at the end of a bar 2. A movable counter contact 3 is fixed to a contact plate 4 and is capable of sliding in the bore of a tubular body 5 consisting of refractory insulating material. This contact is pressed against the stationary contact I by a spring 6 which bears against an insulating plate l. The insulating plate 'l is rigidly connected by means of two bolts 8 and 9 to a flange-like end I0 of the tubular insulating body 5. The bar 2 is extended beyond the ange IIJ and is connected for instance by welding to a current supplying cap II, which forms one external pole of the switch. The movable contact plate 4 is connected to the bolt 9 by means of a exible cable I2. The free end of this bQlt 9 is further Connected by means (Cl. 20D-106) of a cable I3 to a second current supplying cap i4, also for instance by Welding. Guided along the bolts 8 and 9 is an armature I5, preferably of relatively great mass, which, however, is insulated from the said bolts by insulating tubes IE. 5 In order to simplify the assemblage the armature I5 consists of two tubular halves which are held together by any known means. The armature l5 is held in the position shown by a helical spring ll. It is provided at one end with two l0 pins i8 which are adapted to move through bores I9 in a second flange of the tubular insulating body 5. y

Ove1 the outside wall of the preferably tubular vacuum vessel 2D a magnet coil 2l is slipped. l5.

The arrangement operates as follows:

On the magnet coil 2l being energized the armature !5 is drawn into the coil 2l which acts as a solenoid. The first part of the motion takes place quite freely, being opposed only by the ac- 2o tion of the spring l'I. Only when the armature I5 has attained a certain velocity, the pins I8 come in contact with the contact plate 4, whereby the contacts I and 3 are separated with a jerk. The force which is available at the moment of sepa- 2.5 rating thel contacts is of course many times the force which the coil 2l exerts on the armature at the commencement of the motion. Even a very strong weld between the contacts will be broken apart by this sudden impact. 30

In order to avoid the magnetrcoil 2l carrying current during the whole duration of the opening period and to make the switch as safe as possible against vibrations, the movable contact should preferably be arrested in the open po- 35 sition, the coil 2I being at the same time cut out. Such an additional arrangement is also shown in Fig. 1. The contact plate 4 is formed at the side remote from the contact 3 at 22 as a latch. A mating latch 23 which is pivoted at a point 24 40 and is forced by a spring 25 against the latch 22 is provided on one side with a spring extension 26 and, insulated from the latter, a contact 21. A mating contact 28 is connected mechanically and electrically to the bolt 8.

On extensions of the bolts 8 and 9 a second armature 29 is adapted to slide. It is held by springs 30 in the position shown. The two contacts 21 and 28 are connected by flexible leads 3| and 32 with fused-in wires 33 and 34, which 50 extend through the wall of the glass vessel 20. On the outside of the wall of the glass vessel 20 is a second preferably smaller magnet coil 35.

'I'his auxiliary arrangement operates as follows:

When the armature l5 after making contact with the contact plate d has opened the contacts sufciently far, the two latches 22 and 23 enter into engagement. By this means the contacts 21 and 28 are opened at the same moment, thereby interrupting the current iiowing through the magnet coil 2l. The contacts are kept open by the latches 22 and 23 which are in engagement with one another. When the switch is to close, the

`magnet coil 35 is energized and draws the armature 29 in to itself, which by means of a finger 36 depresses the latch 23 in opposition to the spring 25, whereby the latch 22 and with it the movable contact 3 is released and is brought through the action of the spring 6 into contact with the contact l.

In the constructional form shown in Fig. 2 the parts are substantially the same a`s those in Fig. l with the following difference:

An armature 31 with pins 38 is provided, which is loaded by a spring 39. A magnet coil Q0 is provided, which on being energized draws the armaturel 31 into itself, thereby stressing the spring 39. On the circuit being broken, the armature 31 is left to be acted on by the spring 39, so that it experiences a corresponding acceleration and with its pins-38 strikes against the contact plate d, thereby causing the contacts to open.

In the constructional form shown in Fig. 3 the contacts I and 3 are fused into the interior of a glass vessel 4I. One part of this glass vessel is made in the form of an elastic corrugated tube 42. The glass vessel is fixed into a tube 43 in any suitable manner for instance by cement 44. The tube 43 is surrounded by a further tube d5, the two tubes together forming a guide for the armature i5, which, as in the case shown in Fig. 1, can be moved by a. magnet coil 2l in opposition to gravity and in opposition to a spring (not shown), so that its pins I8 strike against the contact plate, causing the contacts lA and 3 to be separated. At $6 stops are indicated for limiting the motion of the contact plate and consequently of the contact 3.

What I claim is:

l. An electromagnetically operatedl vacuum switch comprising a `vacuum tight vessel of substantially cylindrical form having a central longitudinal axis, fixed and cooperating movable contacts arranged on said axis, the latter being adapted to move along the same, a cylindrical insulating member arranged with its axis coincident with the axis of said tube and adapted to surround said contacts, a concentric cylindrical magnetic armature of largeymass compared to the mass of said movable contact surrounding said insulating member, an'anvil xed to said movable contact and adapted to be struck by said armature, spring means for normally pressing said contacts together and a magnet coil adapted on energization` to move said armature rapidly toward said anvil in a direction parallel to the axis of the tube and opposite to the direction of thrust of said pressing means.

2. An electromagnetically operated vacuum switch comprising a vacuum tight vessel of substantially cylindrical form having a central longitudinal axis, xed and cooperating movable contacts arranged on said axis, the latter being adapted to move along the same, a cylindrical insulating member, an anvil xed to said movable contact and adapted to be struck by said armature, spring means for normally pressing said contacts together and a magnet coil adapted on energization to move said armature rapidly toward said anvil in a direction parallel to the axis of the tube and opposite to the direction of thrust ofsaid pressing means, mechanical means within said tube for holding said movable contact in its open position and means for releasing said holding means.

3. An electromagnetically operated vacuum switch comprising a glass vacuum tight vessel of substantially cylindrical form having a central longitudinal axis, fixed andcooperating movable contacts within said vessel arranged on said axis, the latter being adapted to move along the same, a cylindrical magnetic armature of large mass compared to the mass of said movable contact having its axis coincident with that of said vessel and being adapted to move parallel thereto, an anvil fixed to said movable contact and adapted to be struck by said armature, a portion of thewall of said vessel being corrugated and adapted to exert a pressure on said movable contact normally biasing the latter in its closed position, and a magnet coil adapted when energized to move said armature with an impact against said anvil and hold the same in an extended position thereby opening said contacts against the pressure provided by the said corrugated portion of the wall of the vessel.

4. An electromagnetically operated vacuum switch comprising a vacuum tight vessel of substantially cylindrical form having a central longitudinal axis, fixed and cooperating movable contacts arranged on said axis, the latter being adapted to move along the same, a cylindrical insulating member arranged with its axis coincident with the axis of said tube and adapted to surround said contacts, and being provided with an outwardly extending flange at each end, a concentric cylindrical magnetic armature of large mass compared to the mass of said movable contact closely surrounding said insulating member and positioned between the flanges of the same and normally abutting one of them, a helical spring concentrically surrounding said insulating member and arranged between and abutting one of the anges of the same and the armature, an

anvil fixed to said movable contact and adapted to be struck by said armature, spring means for normally pressing said contacts together and a cylindrical magnet coil coaxial with said armature adapted on energization to move said armature rapidly toward said anvil in a direction parallel to the axis-of the tube and opposite to the direction of thrust of said pressing means.

5. An electromagnetically operated vacuum switch comprising a vacuum tight vessel of substantially cylindrical form having a central longitudinal axis, Iixed and cooperating movable contacts arranged on said axis, the latter' being adapted to move along the same, a cylindrical insulating member arranged with its axis coincident with the axis of said tube and adapted to surround said contacts, and being provided with an outwardly extending flange at each end, a concentric cylindrical magnetic armature of large mass compared to the mass of said movable contact closely surrounding said insulating member and positioned between the anges of the same and normally abutting one of -them and means fixed to said armature adapted upon movement thereof to extend through the ange of said insulating member nearest said movable contact, an anvil xed to said movable contact adapted to be struck by said last named means, a helical spring concentrically surrounding said insulating member and arranged between andabutting one of the flanges of the same andthe armature, spring means for normally pressing said contacts together and a cylindrical magnet coil coaxial with said armature adapted on energization to move said armature rapidly toward said anvil in a direction parallel to the axis of the tube and opposite to the direction of thrust of said pressing means.

6. An electromagnetically operated vacuum switch comprising a cylindrical vacuum tight vessel having mounted therein concentric with the longitudinal axis thereof a pair of contacts relatively movable along said axis, an insulating member surrounding said contacts, a cylindrical armature surrounding said insulating member and said contacts and adapted to act upon one of said contacts, and a magnet coil concentric with but outside of said vessel adapted on ener- 10 gization to move said armature.

ERNST ROZUMEK. 

